Treatment planning of adhesive additive rehabilitations: the progressive wax-up of the three-step technique

Transcription

1 CLINICAL RESEARCH Tretment plnning of dhesive dditive rehilittions: the progressive wx-up of the three-step technique Frncesc Vilti, MD, DMD, MSc Privte prctice, Genev Dentl Tem, Genev, Switzerlnd Senior Lecturer, Deprtment of Fixed Prosthodontics nd Biomterils, University Clinic for Dentl Medicine, Genev, Switzerlnd Sylvin Crciofo, MDT Chief Dentl Technologist, University Clinic for Dentl Medicine, Genev, Switzerlnd Correspondence to: Dr Frncesc Vilti Genev Dentl Tem, Rue St-Léger 8, 1205 Genev; Tel.: ; Fx: ; E-mil: 2

2 VAILATI/CARCIOFO Astrct A full-mouth rehilittion should e correctly plnned from the strt y using dignostic wx-up to reduce the potentil for remkes, incresed chir time, nd lortory costs. However, determining the clinicl vlidity of n extensive wx-up cn e complicted for clinicins who lck the experience of full-mouth rehilittions. The three-step technique is simplified pproch tht hs een developed to fcilitte the clinicin s tsk. By following this technique, the dignostic wx-up is progressively developed to the finl outcome through the interction etween ptient, clinicin, nd lortory technicin. This rticle provides guidelines imed t helping clinicins nd lortory technicins to ecome more proctive in the tretment plnning of full-mouth rehilittions, y strting from the three mjor prmeters of incisl edge position, occlusl plne position, nd the verticl dimension of occlusion. (Int J Esthet Dent 2016;11:XXX XXX) 3

3 CLINICAL RESEARCH Introduction When dentition is severely compromised, full-mouth wx-up is generlly considered mndtory to ressure the clinicin tht the cse is comprehensively nlyzed. Unfortuntely, t the end of the therpy, clinicins often relize tht the initil full-mouth wx-up did not correspond to the finl outcome of the rehilittion, to the point tht questions rise s to its rel clinicl vlue. The reson for this my e tht clinicins llow lortory technicins to mke independent decisions out severl clinicl prmeters, which increses the chnce for error. An pproch hs een developed to simplify the full-mouth rehilittion tretment pln the three-step technique which considers three fundmentl prmeters: the verticl dimension of occlusion (VDO), the incisl edge position, nd the occlusl plne position. 1-7 Since the three-step technique dvoctes the principles of minimlly invsive to non-invsive dentistry, n increse of the VDO is strongly dvocted for every full-mouth rehilittion to void the need for tooth preprtion (dditive dentistry). In ddition, the incisl edge position of the finl restortions is essentil to stisfy the ptient s esthetic needs. Finlly, the occlusl plne position not only hs n importnt esthetic vlue, ut lso defines how to shre the interocclusl spce otined with the increse of the VDO t the level of the posterior teeth. In the uthors opinion, full-mouth wx-up where these three prmeters re considered t the sme time is risky. Since the prmeters re closely relted to ech other, chnge to one necessrily entils modifiction to nother. In this wy, the wx-up my ecome useless. For exmple, if mock-up is mde out of the full-mouth wx-up, nd the ptient sks for the incisl edges to e shortened, the occlusl plne must lso e modified to void n unesthetic reverse smile; nd if this ltter spect is modified, the occlusl wx-up should e remde. The full-mouth wx-up hs then ecome useless. The three-step technique prefers, insted, prtil wx-up tht will progress fter eing evluted nd vlidted y the clinicin t severl stges. In lortory step I, the lortory technicin will wx up only the vestiulr spect of the mxillry teeth, nd the clinicin will vlidte only the incisl edges nd the occlusl plne. In lortory step II, wx will e plced on the occlusl surfces of specific posterior teeth, nd the clinicin will pprove the occlusl plne position nd the increse of the VDO. Finlly, in lortory step III, the wx-up will recrete the pltl spect of the mxillry nterior teeth, nd the clinicin will give n opinion on the incisl length nd the increse of the VDO. Step I The esthetic Since stisfying the ptient s esthetic needs is mjor ojective, clinicins should tke the time to relly understnd wht will e considered esthetic for ech ptient. Trying to impose the clinicin s tste on the finl restortions my e highly risky. The risk of not c- 4

4 VAILATI/CARCIOFO Fig 1 nd In cse of the destruction of the incisl edges, it is recommended to involve ptients s soon s possile in the importnt decision out the esthetic of their future smile, since not everyone is redy to ccept longer nd wider restortions. cepting the shpe of the mxillry nterior teeth is higher in ptients ffected y dentl erosion, especilly in severe cses. Although these ptients clim to e disstisfied with their smile, they re often more ccustomed to the look of their irregulr, smll, nd yellowish teeth thn they imgine, nd drstic chnge cn e difficult for them to ccept. To void lengthy discussions nd costly remkes, it is dvisle to identify the shpe nd color of the finl restortions s soon s possile. Lrger, longer, whiter teeth my e shocking for the ptient, nd the initil negtive rection does not lwys chnge to n cceptnce of the new proposed smile design. A tridimensionl mock-up, which lso involves the mxillry posterior teeth, my e more useful to communicte with these ptients (Fig 1). 8 Consequently, in the three-step technique, while fullmouth wx-up is not considered necessry, more extended mock-up is fundmentl step for understnding the ptient s esthetic wishes. This mock-up should e done s soon s possile, efore investing in n extensive wx-up of the posterior teeth. Following the three-step technique, the two csts (out of lginte impressions) re rticulted in mximum interocclusl position (MIP) on semi-djustle rticultor using fceow. The first prtil wx-up will cover only the vestiulr surfce of the mxillry teeth, sufficient to recrete the incisl edges nd the occlusl plne t the level of the mxillry teeth (mxillry vestiulr wxup). Inspired y the photogrphs of the ptient s smile, the lortory technicin will focus exclusively on the esthetic ppernce, with mximum freedom of cretivity (Figs 2 nd 3). Since the rehilittion is driven y minimlly invsive to non-invsive dentistry, lortory technicins should rememer to lwys thicken the teeth during this wx-up so tht the vestiulr spect of the teeth cn e left intct during the preprtion for the finl fcil veneers (dditive wx-up). The use dif- 5

5 CLINICAL RESEARCH Fig 2 nd Mxillry vestiulr wx-up. Only the incisl edges nd the vestiulr cusps of the mxillry teeth re reconstructed in wx, where needed. The ntgonistic cst is not considered t this stge, since efore progressing to the occlusl wx-up, the esthetic occlusl plne should e vlidted cliniclly with the ptient. Fig 3 nd This simplified wx-up is then used to fricte vestiulr mock-up. Thnks to the limited wx on the pltl spect, the mock-up key will e very stle on the teeth, limiting the presence of excesses. Ptients could lso keep the mock-up nd remove it themselves simply y pulling it in the vestiulr direction. c Fig 4 to c Lck of contrst etween the stone nd the wx did not llow for the evlution of the thickness of the future restortions. A silicon index ws necessry to see the vestiulr spce occupied y the wx, which in this specific cse ws insufficient for non-invsive pproch. 6

6 VAILATI/CARCIOFO Fig 5 nd Mxillry vestiulr mock-up. To void ny occlusl preprtion of the mxillry posterior teeth, the dditive wx-up lowers the position of the initil occlusl plne, worsening the existing reverse smile. Thus, efore wxing the occlusl surfces of the posterior teeth, it is mndtory to confirm with the ptient the choice of longer nterior teeth to hrmonize the new occlusl plne. ferent color wx to llow the visuliztion of its thickness is fundmentl (Fig 4). At the completion of clinicl step I, while the ptient expresses n opinion on the look of the mxillry vestiulr mock-up, the clinicin should gther informtion for the restortion of the posterior teeth. In fct, the mjor gol in this mock-up visit is to vlidte the esthetic position of the occlusl plne (eg, hrmony with the incisl edges), so tht the lortory technicin hs helpful informtion on how to shre the posterior interocclusl spce, which will e otined with the increse of the VDO (Fig 5). One of the vrints of clssic clinicl step I occurs in cses where there is n insufficient horizontl overlp of the mxillry nterior teeth. Generlly, to fricte the mxillry vestiulr wxup, wxing up the opposing rch is not considered, since the increse of the VDO hs not yet een decided. However, in cse the mndile hs protrusive position, the mxillry vestiulr wx-up could e used to lso determine the increse of the VDO cliniclly. In this cse, the lortory technicin would e instructed to lengthen the mxillry nterior teeth until their incisl edges overlp the ntgonistic teeth. The incisl edges of the wxed-up teeth should hve miniml horizontl nd verticl overlp (t lest 1.5 mm), nd miniml thickness (1.5 mm), to gurntee the strength of the finl restortions. During the mock-up visit, the clinicin, in ddition to evluting the esthetic outcome of the lengthened teeth, my lso register the ptient s occlusion t the new increse of the VDO y sking the ptient to simply ite on the incisl edges of the mock-up, nd then inject ite registrtion mteril in the posterior sextnts (Fig 6). Another vrint to the clssic threestep pplies in cses ffected y initil/ moderte dentl erosion where the tooth destruction is not sufficiently severe to justify the need for fcil veneers. When the vestiulr spect of the mxillry nterior teeth is mostly intct, nd the ptient cn e restored only y mens of pltl veneers, mock-up visit is not necessry, since the incisl edges 7

7 CLINICAL RESEARCH VDO is more restricted y the risk of set c Fig 6 to c A 23-yer-old ptient ffected y severe dentl erosion. The lortory technicin ws instructed to lso consider the position of the mndiulr rch. During the wx-up, the mxillry incisors were lengthened until miniml overlp with the ntgonistic teeth (1.5 mm) ws chieved. During clinicl step I, with the mxillry vestiulr mock-up in plce, the clinicin evluted whether the length of the mock-up plesed the ptient. In ddition, the ite ws registered y sking the ptient to ite on the mock-up while registrtion mteril ws injected into the posterior spces. nd the occlusl plne of the finl restortions cn esily e visulized with the csts nd the clinicl photogrphs of the ptient s smile. Step I (the mxillry vestiulr wx-up) is then skipped, nd the lortory technicin cn directly strt the wx-up of the posterior qudrnts, reducing the cost nd speeding up the therpy (MODIFIED three-step technique). 9 Step II The posterior support The im of lortory step II is to wx up the posterior teeth t n incresed VDO. This wx-up will involve only the occlusl surfces of the two premolrs nd the first molrs, nd will e used to fricte direct composite restortions y mens of trnsprent keys. At this stge, the clinicin must e prepred to nswer three questions: How much to increse the VDO. How to distriute the posterior interocclusl spce otined with the increse of the VDO. Which posterior restortions to use during step II (direct nd/or indirect restortions). After hving estlished the esthetic occlusl plne in step I, in order to complete the occlusl surfces of the posterior teeth it is necessry to determine the increse of the VDO. As lredy mentioned, in cse of severely worn dentition, n increse of the VDO is inevitle to reduce the need for sustntil tooth preprtion in generl, nd to void elective endodontic tretments, in prticulr t the level of the nterior teeth. Clinicins re generlly frid to increse the VDO, fering consequences t the level of the temporomndiulr joints. On the contrry, the cpcity to dpt to the chnge of the VDO is generlly remrkle However, while for the posterior teeth conspicuous increse of the VDO is lwys fvorle to deliver thicker restortions nd void tooth preprtion, limittions exist in delivering too-ulky nterior restortions to reestlish the contct points. Consequently, the increse of the 8

8 VAILATI/CARCIOFO ting the nterior teeth too fr prt thn y the ptient s poor dptility to the increse of the VDO. Since ech ptient presents different scenrio, creful evlution of the rticulted csts should e considered efore deciding on the increse of the VDO. The threestep technique suggests first mking n ritrry choice y looking t the initil csts mounted on the rticultor. The increse of the VDO should e guided not only y restortive needs, such s the type of restortive mteril selected (eg, cermic or composite), ut lso y occlusl considertions. While deciding on the increse of the VDO, ttention should e pid to hrmonizing the curve of Spee nd correcting the deep ite, especilly in erosive ptients with reverse smile nd suprerupted mndiulr incisors. 15 To fltten the curve of Spee without orthodontic therpy, significnt mount of the spce otined with the increse of the VDO should e given to the mndiulr rch, leving less spce ville for the mxillry posterior teeth. There re two extreme clinicl choices when considering the increse of the VDO (Fig 7). The first choice is to fvor the nterior teeth with miniml increse of the VDO, which will led to rehilittion with dequte finl contct points in the nterior qudrnts, ut thinner nd weker posterior restortions. In ddition, it will e difficult to correct the occlusl plne nd/or the deep ite. The second choice is to fvor the posterior teeth with mximum increse of the VDO, which will otin dequte thickness of the posterior restortions without ny tooth preprtion. At the sme time, it will e possile to hrmonize the occlusl plne nd improve the deep ite. However, the tretment will led to the cretion of n nterior open ite, which cnnot e corrected only y mens of pltl veneers. With the second choice, orthodontic therpy could e considered fterwrds to restore the nterior contcts. The lest-fvorle solution with the second choice is to leve the ptient with n nterior open ite. In this unstle occlusl sitution, Fig 7 The increse of the VDO should e relted to the nterior nd posterior teeth. While for the posterior restortions conspicuous increse is lwys uspicious, for the nterior teeth there is limittion to incresing the size of their pltl spect. 9

9 CLINICAL RESEARCH c d Fig 8 to d Progression of the wx-up to the posterior teeth. The esthetic occlusl plne hd indicted how much of the interocclusl posterior spce could e given to the mxillry posterior teeth. To know how much is left for the mndiulr teeth, the increse of the VDO should e determined first. In this ptient, the ANTERIOR stop ws touching the ntgonistic teeth, nd the posterior spce otined ws considered sufficient to deliver thick-enough posterior restortions. Fig 9 nd Mxillry vestiulr wx-up nd ANTERIOR stop. Thnks to the presence of the ANTER- IOR stop, the posterior teeth were set prt. Their seprtion indicted the mximum possile increse of the VDO, which still llowed for otining nterior contcts. The clinicin should now decide if the interocclusl spce is sufficient for the posterior restortions selected. Note tht the ANTERIOR stop in this ptient lso included mndiulr incisor. 10

10 VAILATI/CARCIOFO Fig 10 nd Progression of the wx-up shown in Fig 9, fter tking the decision on the mount of increse of the VDO. Michign occlusl splint should e worn every night to stilize the nterior contct nd void supreruption. Since the nterior teeth s coupling is the limiting fctor in the increse of the VDO, the lortory technicin should provide n ANTERIOR stop y reconstructing in wx only the pltl spect of the two centrl incisors to the thickest cliniclly cceptle shpe. Only two centrl incisors re necessry to fricte the ANTERIOR stop, since leving the surfces of the djcent teeth free of wx llows for etter judgment on the clinicl cceptility of the ulkier pltl surfces. With the models mounted on the rticultor, the clinicin cn visulize the interocclusl spce otined in the posterior sextnts when the csts touch t the level of the reconstructed centrl incisors, since this represents the mximum mount of the VDO possile to still reestlish nterior contcts. The clinicin should then decide if this increse of the VDO is sufficient for the restortive needs of the posterior teeth or not, nd mke the clinicl choice of fvoring either the nterior or the posterior teeth (Figs 8 to 10). If the mndiulr nterior teeth present exposed dentin, they should lso e included in the tretment nd in the ANTERIOR stop. For the mndiulr (s well s the mxillry) nterior teeth, only few strtegic teeth should e wxed up (ie, the most vestiulr ones), to etter visulize the clinicl outcome. Thnks to this prtil wx-up, mlpositioned teeth cn e etter identified, nd the need for orthodontic therpy my e dvocted. While reconstructing dmged mndiulr teeth in wx, the lortory technicin should e creful not to lengthen their incisl edges excessively, since these teeth often lredy present suprerupted position. In ddition, lengthening these teeth in the incisl direction will worsen the curve of Spee nd the verticl overlp (deep ite) (Fig 11). To fricte n ANTERIOR stop, three points should e identified: A Incisl edge of the finl restortion. B New contct point with the ntgonistic tooth fter n increse of the VDO. C Most cervicl mrgin of the finl restortion. 11

11 CLINICAL RESEARCH Fig 11 Restortion of the nterior teeth nd deep ite. To void worsening the deep ite, the clinicin nd lortory technicin should resist the tempttion to excessively lengthen the incisl edges of oth the mxillry nd mndiulr teeth. In prticulr, the mndiulr incisors re often suprerupted, so insted of lengthening their incisl edges, the contct point should e reched y thickening the pltl spect of their ntgonistic teeth. Fig 12 Three points could e identified in n ANTERIOR stop. A decision on the position of the B point (new contct point t the increse of the VDO) should involve the clinicin, since the finl shpe my e ulkier thn nturl tooth, to llow for lrger increse of the VDO. The clinicin should determine whether the new shpe is cliniclly cceptle to the ptient. The union of these three points defines the pltl shpe of the mxillry pltl restortions. The junction etween B nd C should e s stright s possile to void phonetic impirments nd plque ccumultion (clensility), ut to still gurntee support to the occlusl contct (mechnicl strength) (Fig 12). It is recommended tht the pltl wxup e kept inside verticl line pssing through the C point (the C line), plced on frontl plne. This line defines the most pltl limit where the occlusl contct (B point) could e plced (Fig 13). 12

12 VAILATI/CARCIOFO Fig 13 nd Incorrect ANTERIOR stops. In oth cses, the B point ws more pltl thn the C line, nd this shpe for the finl restortions would not hve een tolerted y the ptient. With just this miniml wx-up, the clinicin hs gined vlule informtion on the increse of the VDO nd the reestlishment of the nterior contct points. The three-step technique recommends the rticultion of the models in MIP. However, for more complex cses (eg, devited mndile), it is possile to reregister the position of the mndile t the incresed VDO during the mock-up visit, thnks to the presence of the AN- TERIOR stop, which could lso e used s n nterior jig. While the ptient is iting on the ANTERIOR stop, the interrch posterior spce is filled with registrtion mteril. The mndiulr cst cn then e remounted, since the occlusl spect of the posterior teeth is prtilly not covered y the mock-up, nd the occlusl ite registrtions could e dpted on the models (Fig 14). While deciding on the increse of the VDO, the clinicin should lso consider how to distriute the otined interocclusl spce mong the posterior teeth. This decision will mostly e sed on the presence of exposed dentin (eg, teeth to e restored), nd the finnces of the ptient. The uthors elieve tht it is lso importnt to fltten the occlusl plne nd reduce the deep ite whenever possile to promote more freedom to the lterl excursions of the mndile. 15 c Fig 14 to c An ANTERIOR stop could ecome n nterior jig during the mock-up visit to rerticulte the csts t incresed VDO (cse completed with Dr. C Dmrdji). 13

13 CLINICAL RESEARCH Fig 15 The est view to nlyze rticulted csts is from the pltl/lingul spect. While lortory technicins re fmilir with this view, clinicins re not, since it is impossile cliniclly. From this view it is esier to visulize the occlusl plne, the curve of Spee, nd the suprerupted mndiulr nterior teeth. The posterior interocclusl spce could e shred in three different wys: 1) one-rch distriution; 2) two-rch distriution; 3) mixed distriution (Fig 15). One-rch distriution With this option, the spce is given to only one rch (mndiulr or mxillry). The dvntge of this option is the reduction in the overll cost of tretment, since only one rch is restored. In ddition, the spce otined y the increse of the VDO will not e shred mong ntgonistic teeth. Consequently, the increse of the VDO could e kept smller, nd the open ite corrected more esily y mens of pltl veneers. Unfortuntely, this option is not lwys possile due to clinicl limittions. For exmple, the posterior teeth of the unrestored rch should e intct (no dentin exposure), nd the existing occlusl plne of the ntgonistic teeth should e correct (Fig 16). Fig 16 nd One-rch distriution. The increse of the VDO required to repir the incisl edges ws miniml. Since the mxillry posterior teeth were intct, it ws decided to increse the VDO, restoring only the ntgonistic mndiulr teeth. 14

14 VAILATI/CARCIOFO Fig 17 nd Two-rch distriution. A moderte to severe cse of dentl erosion. Both the rches presented teeth with exposed dentin, so two-rch distriution ws necessry, requiring more spce t the level of the posterior teeth. Two-rch distriution This is the most common sitution, especilly in the cse of severe dentl wer, since unfortuntely the posterior teeth of oth the rches present exposed dentin nd need to e restored. The dvntge of this option is the possiility of chnging the position of the occlusl plne y modifying oth the occlusl surfce of the mxillry nd mndiulr posterior teeth. One disdvntge is the cost, since the ptient hs to py for full-mouth rehilittion, with the restortion of ll the posterior teeth. Another disdvntge is the necessity to shre the interocclusl spce otined with the increse of the VDO. For exmple, if 2 mm is ville t the level of the first molr, the two ntgonistic onlys shring the ville spce eqully will only hve 1-mm thickness, which my not e strong enough, especilly in ptients with prfunctionl hits (Fig 17). Mixed distriution This distriution mens tht oth the mxillry nd mndiulr posterior teeth will e restored, ut not ll of them. This is often the cse when there is n irregulr occlusl plne, with supreruption of some posterior teeth. To chieve correct occlusl plne, the suprerupted teeth will not e restored, if of course their occlusl surfce is intct. The dvntge of this option is tht it costs less nd hs shorter clinicl time compred to the two-rch distriution (Fig 18). Before the lortory technicin strts the wx-up of the posterior teeth, the clinicin should lso hve n ide out which type of restortions will e delivered during step II provisionl nd/or finl so tht the wx-up cn e modified ccordingly. In this rticle, only the wx-up modifictions in cse of friction of provisionl restortions re discussed. When the dentition is prticulrly compromised nd/or mndiulr devition is present, it is preferle during step II to deliver provisionl posterior composite restortions, fricted directly in the mouth y mens of trnsprent keys. This tretment is comprle to n occlusl ite onded for 24 h in 15

15 CLINICAL RESEARCH Fig 18 nd Mixed distriution. In this erly cse of dentl erosion, the increse of the VDO ws miniml nd necessry mostly to reinforce the thin incisl edges. To reduce the numer of teeth to e restored nd to void shring the limited posterior interrch spce, only the mndiulr molrs nd the mxillry premolrs were restored. It ws possile to not include the remining posterior teeth in the rehilittion, since they did not present dentin exposure. Note tht the wx-up of the pltl spect of ll the mxillry teeth ws not necessry. The ANTERIOR stop could e done with only one or oth centrl incisors. the mouth (therpeutic white ite). This is lso the fstest tretment to restore multiple teeth t the sme time (eg, in two-rch distriution) for ptients who do not hve time or cnnot tolerte long ppointments. Following the three-step technique, these provisionl restortions will e replced fter the rehilittion of the nterior qudrnts y the finl restortions. When the wx-up of the posterior teeth is used for the friction of the provisionl restortions, it should e modified t four levels efore the friction of the trnsprent keys: 1) interproximl res; 2) mesil nd distl stops; 3) occlusl emrsures (mrginl ridges); nd 4) vestiulr/pltl surfce (one-third cervicl). In generl, the wx should e kept to minimum nd plced only on the occlusl surfces where the contct points of the white ite will e. The remining wx should e removed efore the friction of the keys to reduce the size of the provisionl composite restortions nd fcilitte their future removl. In ddition, the interproximl res should e clen of excess wx, to reduce the risk of interproximl excesses during the friction of the composite restortions. A mesil nd distl stop should lwys e identified nd left wxfree, to promote etter sitting of the trnsprent keys (ie, less occlusl djustments). Dmged vestiulr nd/or pltl surfces my lso represent dilemm during the wx-up. The lortory technicin should resist the tempttion of fully reconstructing in wx these dmged surfces, since the clinicin does not need to fricte the provisionl composite so close to the cervicl spect of the teeth (high risk of excess) (Fig 19). The only reson to extend the wx-up to the cervicl spect is if the supporting cusps re very compromised (eg, 16

16 VAILATI/CARCIOFO Fig 19 nd For white ite, the wx should e limited to the occlusl surfces only, even when the teeth re not intct in the cervicl third. This will gurntee etter onding conditions nd esier removl of the excesses. Fig 20 nd The posterior wx-up to fricte the trnsprent keys should e very precise t the level of the emrsures. Any excess of wx will led to n excess of composite in the mouth. The mrginl ridges could e wekened with sclpel to promote the opening of the contct points etween the direct restortions during mstiction. pltl mxillry cusps), nd the occlusl contcts of the white ite need to e reinforced (ie, void sher filure). One of the limits of the white ite is the closed interproximl contct points. To try to fvor their opening during function, the occlusl emrsures of the wx-up could e wekened y ccentuting the seprtion of the wxed-up mrginl ridges with sclpel (Fig 20). Finlly, it is worth rememering to lwys use different color wx, since the clinicin will use the contrst with the stone to get n ide of how much composite should e plced in the trnsprent keys (Fig 21). At the end of clinicl step II, ptients will present stle posterior support t n incresed VDO nd n nterior open ite. Thnks to this nterior spce, the mxillry nterior teeth will then e restored without ny tooth preprtion (mximum tooth preservtion) y mens of pltl veneers (step III). To move to 17

17 CLINICAL RESEARCH Fig 21 The use of similr color etween the wx nd the cst mkes it very difficult to see the limits of the wx nd its thickness. Note tht the mxillry cnine is not free of wx, nd if this is not removed, the trnsprent key will not hve its mesil stop. the next step, new impressions, n nterior ite registrtion in MIP, nd fceow re needed. Step III The nterior contcts In step III, the lortory technicin will recrete in wx the pltl surfces of the mxillry nterior teeth efore fricting the pltl veneers. The shpe of the two centrl incisors ws lredy proposed with the ANTERIOR stop, nd confirmed or chnged y the clinicin (Fig 22). As previously mentioned, one of the dvntges of the three-step technique is the possiility of evluting nd, if necessry, correcting the outcome of previous steps. The increse of the VDO, otined during step II, could e modified during step III. In cse the lortory technicin relizes tht the clinicl increse of the VDO ws excessive to reestlish the nterior contcts y mens of pltl veneers, he/she cn progress with the friction of the finl nterior restortions to the idel shpe, which will hve no contcts with the ntgonistic teeth. The clinicin will then ond these restortions nd djust the occlusion on the posterior teeth until the nterior teeth re in contct (decrese of the VDO). It is lso possile to correct the opposite sitution (increse of the VDO). In this scenrio, the VDO will e incresed on the rticultor y dding wx on the posterior teeth, nd the pltl veneers will e fricted ccordingly. Once onded on the pltl veneers, s expected, the posterior teeth will no longer e in contct. To reestlish the posterior support, simple direct composite will e delivered y dding mteril on the previously roughened surfces of the pre-existing contct points. To fcilitte this second option, the direct composite restortions should e mde in only one rch. If mjor increments of the VDO re necessry, new trnsprent keys could e used to speed up the tretment (Fig 23). Severl uthors hve set fundmentl guidelines for the reconstruction of the pltl surfces of the mxillry nterior teeth, especilly considering the envelope of function However, following the three-step technique, the shpe of the mxillry nterior finl restortions is strongly dictted, not only y restoring the dmged pltl spect, ut lso y the need to estlish the nterior contcts fter the increse of the VDO. To chieve these contcts, 18

18 VAILATI/CARCIOFO Fig 22 Wxing up the centrl incisors to fricte the ANTERIOR stop llows the lortory technicin to discuss the shpe of the future pltl veneers. At this stge, the clinicin cn sk for modifictions or ccept the proposed form. Fig 23 In this cse, the increse of the VDO otined with the white ite ws not sufficient. Insted of rescheduling the ptient, with the sme impression for the pltl veneers, the lortory technicin wxed up the occlusl surfces of the mxillry teeth nd fricted the pltl veneers t the incresed VDO. Two trnsprent keys were used to increse the VDO efore onding the veneers. there is no hesittion to restore teeth to lrger size thn the nturl dentition. In ddition, clinicins often hve to fce nd solve dentl/skeletl discrepncies improved or ggrvted y the increse of the VDO y using restortive mens only, since this type of ptient ccepts the therpy ecuse of its simplicity (nd rpidity), nd frequently refuses orthodontic therpy nd even more frequently, orthognthic surgery. Therefore, the lortory technicin will rrely e inspired y the nturl dentition for the nterior region of the mouth, nd will recrete the perfect shpe nd idel contct points. Overll, the restored teeth will lwys look wider in n nterior posterior direction thn the nturl dentition, nd lortory technicins should not feel uncomfortle out delivering restortions with n unusul shpe. Even though it is expected tht the pltl spect of these restored teeth should not resemle the intct teeth, ppering thicker even t the incisl edges, there re limittions to how much the size cn e incresed. There re six mjor ojectives during step III (friction of the pltl veneers): Re-estlish nterior contcts points (B points), unless decided otherwise. Supported B points (eg, not on surfces tht re too inclined). BC line stright (for clensility nd phonetics). Smooth pltl surfces (no excessive ntomy). Mximum effort to correct or not ggrvte deep ite (minimum lengthening of oth the incisl edges of mxillry nd mndiulr teeth). No steep nterior guidnce (open incisl ngle). 19

19 CLINICAL RESEARCH Fig 24 nd Pltl veneers with pltl ntomy tht is too ccentuted, occupying spce for the tongue without ny functionl purpose. In ddition, these veneers could e very uncomfortle for ptients who re ccustomed to concve shpe of eroded teeth. While defining the mximum thickness tolerted y ech ptient, lortory technicins should er in mind tht ptients ffected y dentl erosion re used to hving very flt/concve pltl surfces, nd tht they hve dpted the tongue to spek even with conspicuous loss of tooth structure, since this loss hs hppened progressively t very slow rte. Occupying the tongue spce with ulky pltl veneers ll t once will e immeditely considered uncomfortle y the ptient, especilly ecuse it would cuse the impirment of the pronuncition of some letters (eg, D-T sounds). In time, the tongue will eventully djust, ut there will e ptients who will struggle for longer, nd who my pnic in the mentime. As generl rule, since the finl shpe will e igger, the size of the pltl surfces should e kept flt in the res cerviclly to the B point (stright BC line). Complicted occlusl ntomy should e voided, such s very deep pltl grooves nd/or pronounced cingul. In ddition, not only is more effort required, ut the surfces of the finl restortions will e more difficult to polish, nd the irregulr texture will e very uncomfortle for the ptient s tongue (Fig 24). During the friction of the ANTER- IOR stop, the lortory technicin focused only on sttic occlusl contcts, mostly nlyzing the shpe of the pltl surfce etween the B nd C points for clensility nd prolems with phonetics. In this lortory step III, the surfce, comprised etween the B nd A points, will lso e considered, since this is the re involved in the eccentric movements (nterior guidnce). Severl uthors hve given guidelines to correlte the condylr inclintions with the steepness of the nterior guidnce, nd it is not the ojective of this rticle to nlyze the vlidity of the different methods to chieve correct occlusl scheme, especilly when there is no evidence to support the superiority of one method over the others

20 VAILATI/CARCIOFO Fig 25 Incisl ngle. This ngle is defined y the AB line (from the contct point to the incisl edge) nd the fcil surfce of the ntgonistic tooth. In the cse on the right, the incisl edges re too thick. Reducing their volume without compromising the mechnicl strength of the future pltl veneers will open the incisl ngle nd promote the freedom of the mndile in its functionl movements. Fig 26 To open the incisl ngle (1), the A point is moved more vestiulrly (2). The pltl veneer will stop with step (2), which will e filled y the composite used during the onding procedure to smooth the trnsition nd improve the shde mtching with the remining tooth structure (3). As generl rule, since rigid rticultor cnnot duplicte the sophisticted mndiulr movement, the three-step technique promotes the use of the ptient s the finl rticultor to test the occlusion. Consequently, occlusl djustments in the mouth will lwys e required nd expected. 21 The use of composite for the therpeutic ite nd the pltl veneers fcilittes this tsk. The eccentric movements re simply tested with the ptient sitting upright, not nesthetized, nd chewing smll piece of gum. It is very surprising how ptients know exctly which re the interferences during chewing when they re not nesthetized. Following the ptient s request, group function is often the pre- 21

21 CLINICAL RESEARCH ferred choice over cnine guidnce, especilly in horizontl chewers. 15 Since the eccentric movements will e tested in the mouth, the lortory technicin is instructed to only reduce the steepness of the incisl guidnce, dopting n ritrry condylr inclintion of 30 degrees. One method to reduce the steepness is to resist the tempttion of rejuventing the smile, nd to lengthen the teeth indiscrimintely in every ptient (without considering the initil sttus nd/or the presence of prfunctionl hits). To help visulize the steepness of the nterior guidnce, n incisl ngle could lso e identified y trcing the AB line nd intercepting it with the vestiulr surfce of the mndiulr ntgonistic tooth (incisl ngle) (Fig 25). To open the incisl ngle, the lortory technicin my lso reduce the thickness nd/ or move the position of the incisl edges fcilly. The pltl veneers will then join the vestiulr surfce with step, which will e filled with the hyrid composite used to ond the veneers. In this mnner, not only will the nterior guidnce e less steep, ut the color mtch will lso e improved, without the need for chmfer preprtion (Fig 26). Conclusion A full-mouth wx-up is considered necessry step for the correct tretment plnning of full-mouth rehilittion. Unfortuntely, when sking for comprehensive wx-up, clinicins delegte importnt decisions to their lortory technicins, who re not experienced/ knowledgele enough to choose from the different options nd consider their clinicl implictions. As result, the risk of remkes nd misunderstndings increses. The simplified pproch tht hs een developed the three-step technique promotes n ctive interction etween the clinicin nd the lortory technicin through the progressive development of the wx-up. This technique frgments the wx-up of the full-mouth rehilittion into stges, nd llows the clinicin to cliniclly vlidte the lortory technicin s choices. Thnks to the simplicity of the three-step technique, criticl prmeters such s the incisl edges, the occlusl plne, nd the VDO cn e correctly evluted, nd the finl tretment pln is visulized progressively with the progression of the wx-up nd the gthering of more clinicl informtion. Acknowledgments The uthors would like to thnk Professor Iren Siler for elieving in nd supporting the concept of the three-step technique t the University of Genev. Thnks to ll the lortory technicins who hve contriuted with their pssionte work to the development of the three-step technique nd the cretion of this rticle, eing: Sylvin Crciofo, Alwin Schonenerger, Ptrick Schnider, Pscl Muller, August Bruguer, Serge Erpen, Vincent Locultre, Giuseppe Dolce, Romeo Pscett, nd Giuseppe Romeo. 22

22 VAILATI/CARCIOFO References 1. Vilti F, Bruguer A, Belser U. Minimlly invsive tretment of initil dentl erosion using pressed lithium disilicte glss-cermic restortions: cse report. QDT 2012: Grütter L, Vilti F. Full-mouth dhesive rehilittion in cse of severe dentl erosion, minimlly invsive pproch following the 3-step technique. Eur J Esthet Dent 2013;8: Vilti F, Belser UC. Pltl nd fcil veneers to tret severe dentl erosion: cse report following the three-step technique nd the sndwich pproch. Eur J Esthet Dent 2011;6: Vilti F, Vglio G, Belser UC. Full-mouth minimlly invsive dhesive rehilittion to tret severe dentl erosion: cse report. J Adhes Dent 2012;14: Vilti F, Belser UC. Fullmouth dhesive rehilittion of severely eroded dentition: the three-step technique. Prt 3. Eur J Esthet Dent 2008;3: Vilti F, Belser UC. Fullmouth dhesive rehilittion of severely eroded dentition: the three-step technique. Prt 2. Eur J Esthet Dent 2008;3: Vilti F, Belser UC. Fullmouth dhesive rehilittion of severely eroded dentition: the three-step technique. Prt 1. Eur J Esthet Dent 2008;3: Mgne P, Belser UC. Novel porcelin lminte preprtion pproch driven y dignostic mock-up. J Esthet Restor Dent 2004;16: Vilti F, Crciofo S. CAD/ CAM monolithic restortions nd full-mouth rehilittion to restore ptient with pst history of ulimi: the modified three-step technique. Int J Esthet Dent 2016;11: Aduo J. Sfety of incresing verticl dimension of occlusion: systemtic review. Quintessence Int 2012;43: Wlther W. Determinnts of helthy ging dentition: mximum numer of ilterl centric stops nd optimum verticl dimension of occlusion. Int J Prosthodont 2003;16(suppl): Gross MD, Orminer Z. A preliminry study on the effect of occlusl verticl dimension increse on mndiulr posturl rest position. Int J Prosthodont 1994;7: Kohno S, Bndo E. Functionl dpttion of mstictory muscles s result of lrge increses in the verticl occlusion [In Germn]. Dtsch Zhnrztl Z 1983;38: Crlsson GE, Ingervll B, Kock G. Effect of incresing verticl dimension on the mstictory system in sujects with nturl teeth. J Prosthet Dent 1979 Mr;41: Plns P. Réhilittion neuro-occlusle RNO, ed 2, Group Liisons, Lundeen HC, Shryock EF, Gis CH. An evlution of mndiulr order movements: their chrcter nd significnce. J Prosthet Dent 1978;40: Celenz FV. The centric position: replcement nd chrcter. J Prosthet Dent 1973;30: Borgh O, Posselt U. Hinge xis registrtion: experiments on the rticultor. J Prosthet Dent 1958;8: Grcis S. Clinicl considertions nd rtionle for the use of simplified instrumenttion in occlusl rehilittion. Prt 1: Mounting of the models on the rticultor. Int J Periodontics Restortive Dent 2003;23: Grcis S. Clinicl considertions nd rtionle for the use of simplified instrumenttion in occlusl rehilittion. Prt 2: setting of the rticultor nd occlusl optimiztion. Int J Periodontics Restortive Dent 2003;23: Wiskott HW, Belser UC. A rtionle for simplified occlusl design in restortive dentistry: historicl review nd clinicl guidelines. J Prosthet Dent 1995;73: Dwson P. Evlution, Dignosis, nd Tretment of Occlusl Prolems, ed 2. St Louis: Mosy, 1989: Hoo S. Formul for djusting the horizontl condylr pth of the semidjustle rticultor with interocclusl records. Prt II: Prcticl evlutions. J Prosthet Dent 1986;55: Hoo S. Formul for djusting the horizontl condylr pth of the semidjustle rticultor with interocclusl records. Prt I: Correltion etween the immedite side shift, the progressive side shift nd the Bennett ngle. J Prosthet Dent 1986;55: Wiskott HWA (ed). Fixed Prosthosdontics, Principles nd Clinics. London: Quintessence, Koyno K, Tsukiym Y, Kuwtsuru R. Rehilittion of occlusion science or rt? J Orl Rehil 2012;39: